简介：

简介：Ageneralizednon-stationarycurvesubdivision(GNSforshort)schemeofarbitraryorderk≥3withaparameterhasbeenproposedbyFangetal.inthepaper(FangMei-eetal.,CAGD,2010(27):720-733).IthasbeenprovedthattheproposedschemeoforderkgeneratesCk-2continuouscurvesfork≥4.Buttheproofofthesmoothnessinthispaperisuncompleted.Moreover,theC1-continuityofthethirdorderschemehasnotbeendiscussed.Forthisreason,inthispaper,weprovideafullcorrectedproofofthesmoothnessoftheGNSschemeoforderkfork≥3.

简介：Parametricinstabilityofariseriscausedbyfluctuationofitstensionintimeduetotheheavemotionoffloatingplatform.Manystudieshavetackledtheproblemofparametricinstabilityofariserwithconstanttension.However,tensionintheriseractuallyvarieslinearlyfromthetoptothebottomduetotheeffectofgravity.Thispaperpresentstheparametricinstabilityanalysisofdeepwatertop-tensionedrisers(TTR)consideringthelinearlyvaryingtensionalongthelength.Firstly,thegoverningequationoftransversemotionofTTRunderparametricexcitationisestablished.ThisequationisreducedtoasystemofordinarydifferentialequationsbyusingtheGalerkinmethod.ThentheparametricinstabilityofTTRforthreecalculationmodelsareinvestigatedbyapplyingtheFloquettheory.TheresultsshowthatthenaturalfrequenciesofTTRwithvariabletensionareevidentlyreduced,theparametricinstabilityzonesaresignificantlyincreasedandthemaximumallowableamplitudeofplatformheaveismuchsmallerunderthesamedamping;Thenodesandantinodesofmodeshapearenolongeruniformlydistributedalongtheaxialdirectionandtheamplitudealsochangeswithdepth,whichleadstocouplingbetweenthemodes.Thecombinationresonancephenomenonoccursasaresultofmodecoupling,whichcausesmoreseriousdamage.

简介：Anon-linecontrolmethodofsurfacequalityforcontinuoushot-dipgalvanizedsteelstripaftercoolingispresented,whichcombinesanalyticaldynamicstheoryofathinplatewiththefiniteelementmethod.Theinherentcharacteristicsofthenon-immersedandpartiallyimmersedstripinliquidzincwerecalculatedonthebasisoftheoreticalanalysisandnumericalsimulation,respectively.Multi-parameterfittingofthedeviationbetweenresultsusingdifferentmethodswasperformed.Tooptimizethestripexcitationfrequencyawayfromtheresonanceregion,on-linevibrationcontrolofthestripneartheairknifeunderfullproductconditionswasachievedbychangingthefieldproductionparametersbasedonthefieldtestresults.Theresultsindicatethatalthoughtheaxialvelocityhaslittleeffectontheinherentcharacteristicsofthestripcomparedwithothermanufacturingparameterssuchasthesteelspecificationsandtension,itinducesexternalexcitations,includingmovingtheaerodynamicloadandbearingvibration.Tosomedegree,thevibrationneartheairknifecanbereducedbystrengtheningthesupportstiffnessofthecontactrolls.Atotalon-linecontrolprogramofsurfacequalityforcontinuoushot-dipgalvanizedpureZnandgalvannealedsteelsheetinthecoolingsectionisproposed.

简介：Twinninganddetwinningaretheimportantdeformationmodesinmagnesiumalloysduringcyclicloadingatroomtemperature.Toanalyzethesetwodeformationmechanism,cycliccompression–tensionexperimentswereperformedonMg–3Al–1Znrolledsheetalongtherollingdirection.Inthesetests,themicrostructureevolutionsofaseriesofgrainsduringdeformationweretracedbyusingquasiinsituelectronbackscatterdiffraction(EBSD).ImportantquantitiesliketheSchmidfactorsoftwinningsystem,thefractionoftwinningduringcompression,andthefractionoftwinningafterreverseloadingwerecalculatedonthebasisofmeasuredquantities.TheinfluenceofSchmidfactoroftwinningvariantsondetwinninguponreverseloadingwasanalyzed.DetwinningwouldprefertoproceedduringreverseloadingiftheSchmidfactoroftwinninginthetwinningareabeforereverseloadingissufficientlylarge.